homebrew CNC plasma cutter?

would just like to put an idea out there.. get some feedback. i have a small inverter plasma cutter.. it can handle about
1/4" if i take it slow.
was thinking it would make an interesting project to make an X-Y cross slide type table.. and make a holder for the gun. two small motors and another set of wires for the trigger and i might have a little CNC cutter. maybe just something to cut nice clean circles out of sheetmetal for now.
even just the torch on a linear slide would be nice for making straight consistent cuts.
i wouldn't want to permanently modify the plasma cutter.
only problem i forsee is ensuring that the torch is cutting. sometimes when cutting freehand i have to push the button again (it has some lag) to get it restarted.
-tony
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The biggest problem you face is isolating the High frequency from your motors and controls.

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Go to the Plasmacam website and look at what they are doing.
http://www.plasmacam.com /
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(Snip)

During an open house at the NASA Ames model shop held several years ago, the folks there explained that their first NC plasma cutter suffered from CPU resets caused by voltage spikes sourced at the torch tip. Massive shielding and bypassing helped immensely.
--Winston
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snipped-for-privacy@removedotfononica.com says...

Making it computer controlled would be rather involved (Though not impossible). Worse though is getting it to work with available software or writing your own!
What I'd like to see is that second thing, just the X/Y slides with no CNC. It would be a plasma version of a router "duplicator". It would only be 2 axis instead of three. That way I can print stuff out on a printer, then tape that to the "source" area of the table and merely trace it with a stylus connected to the duplicator carriage.
Currently I am doing the print/glue/cut thing, but on delicate areas, the paper all burns away leaving me to wing it.
I plan on designing it myself if I can't find plans, but... finished plans would be nice! :)
Larry A
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For simple patterns do a broken-arm pantograph cutter.
We have one at school for flame cutting.
You make a pattern out of thin steel and the magnetic follower crawls around the edge of your pattern, with the torch below.
http://www.koike.com/images/ik54d_large.jpg
http://www.koike.com/products/Pdf%20Files/IK54D.pdf
Lowbuck tools sells a kit for making one.
http://www.lowbucktools.com/flamecut.html http://www.lowbucktools.com/fckit.html
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snipped-for-privacy@ntlworld.excessbit.com says...

Hey the 380! Same as I have.
Someone replied with an interesting duplication setup, but I am generally doing all one-off items for special projects so really just needed something to do the tracing. If I can actually get my hands on the HF router duplicator I could see how feasable it would be to modify it a bit to work with the cutter, but the local store doesn't have any in stock or on display.
Say you haven't tried using the "Fine cut" nozzle on the 380 have you? Was wondering how those work... (I could always just buy one I guess :)
Larry
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Larry
no - I have no knowledge of this. I have the machine "as supplied" and am still getting used to its very useful capabilities.
Richard Smith
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Larry
If only all plasma cuts were like those you get easily on mild steel! The virtually unique thing about iron is that its oxide melts at a lower temperature than the metal - aobut 1300C oxide vs. 1700C metal. Makes for a very easy cutting and welding ability.
After cutting mild steel, if it needs dressing at all, I have a lttle hammer about the size of a toffee hammer, which I use to go along tapping on the lower edge of the cut face. Then edge so clean.
If only.
Would others agree that stainless is much more sensitive in its correct cutting paramenters and that such a perfect result is difficult to achieve?
Richard Smith
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snipped-for-privacy@jabble.com says...

No, their web site has done this to me before. I saw it in their catalog. I once tried to find a cold saw on their site that was in a recent catalog but it wasnt there (or the local store) either :(
This is the sort of thing that I was talking about
http://www.wood-carver.com /
Though the HF one seemed to have more distance between the stylus and the router...
Larry
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says...

Here is a scan of the catalog:
http://www.phoca.com/lj/RouterCopier.jpg
Something that worries me is the fact that is doesn;t seem to use rollers, meaning that it may require a heacy hand to move it around (Even without a router attached)
To be useful for a plasma cutter, I think it would have to have a pretty light touch, which is why I wanted to see one in the store.
Larry
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Yup, I think that almost anything can happen at Harbor Freight. That something would be in a catalog and not on their web site doesn't surprize me. I have found the same items on different pages and at different prices. With the same part number.
And it is an interesting item. And the price is sure tempting. Mebbe it could be improved? Add a few roller bearings?
I tend to think of HF stuff as pre-built kits. They should be taken apart and rebuilt, only better. But at the right price........
Thank you for scanning the page in. But can you give the whole part number so I can start annoying them locally?
Thanks again,
-jim
says...

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Great! Thank you!
How did you find it? 'Router','duplicator' and 'copier' didn't work aas key words.
I downloaded the manual and here's an interesting sentence; "Ball bearing movement and counterweighted attachment results in a smooth operating and accurate machine. "
Think it's really any good?
Their return policy is pretty good, so maybe I'll screw up my courage and go for it.
-jim
says...

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jjjjj wrote:

Glad it helped, all I did to find it was look at your scanned ad and use "carving reproduction machine" as the google terms.
Bob
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First you have to get through HF trying to sell you magazines of all things...
Steve Smith
jjjjj wrote:

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I built a homemade cnc plasma gantry a few years ago and use it all the time. It is similar to an early model that Torchmate sells, but highly modified. I use a Hypertherm 850 plasma machine with a machine torch (although you could build a holder for a hand torch). I have a lot more photos that will go up this week so stay tuned. You can see it at:
http://www.texasmetalcraft.com
I also uploaded a movie that shows it cutting (movie of the month)...but it is large...so you need broadband.
I tackled the high-frequency EMC problem messing up the computer and electronics and have some good tips for fixing the problem if anyone wants them. I'll be happy to share any info I have learned over the years about homemade cnc plasma gantrys. I've cut stuff as small as Texas shaped key chains (under 1") to 48" clock dials....and from thin sheet metal to 1/2" plate.
Randy Ray www.texasmetalcraft.com
says...

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Randy - That is a great movie. - Or at least very nice to see and love the credits !
Any info on the EMI or EMC - would be useful.
Thanks, Martin
Randy Ray wrote:

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer snipped-for-privacy@pacbell.net
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I have had several folks email me about clearing up the EMC problems with the CNC plasma system and the gantry system I built. Instead of answering them all individually or appending here with just words, I am in the process of updating my website (www.texasmetalcraft.com). If I don't get it finished by the end of next week and have a bunch of the stuff explained (with pics), I'll post it here (and point to the pics). Bear with me. I am in the process of doing the same with my TIG welder as it also effects my computers and electronics that are in close proximity. So far the only thing I'm having a tought itme with is that the TIG welder freezes my electronic thermostat for my AC unit in the garage. The thermostat is within 3 feet of the TIG and grounding/shileding it is difficult. Randy
snipped-for-privacy@randyray.com (Randy Ray) wrote in message says...

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Randy Ray wrote:

I get my power to most of the shop shut off due to a Ground Fault circuit within it.
I currently think it is a current developed in the ground that isn't to be there. My unshielded 220 line runs three feet from the main breaker for the GF circuit.
I might try putting the cable in a grounded tray or rack... experiments.
Martin
--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer snipped-for-privacy@pacbell.net
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